Answer: The Option "d.returning inventory that is defective or broken" is NOT an example of safeguarding inventory.
Explanation: If we analyze the statements:
a.physical devices such as two-way mirrors, cameras, and alarms - These are all tools intended for protection against possible inventory theft.
b.storing inventory in restricted areas - Restricting access only to inventory-enabled personnel is able to protect the inventory much more than if anyone can access it.
c.matching receiving documents, purchase orders, and vendor's invoice - Controlling each of the purchase documents and performing the physical count reduces the possibilities of inventory differences for losses or errors.
d.returning inventory that is defective or broken - Returning the defective inventory is a post-echo action that occurred due to the unprotection of the inventory, therefore it could not be referred to as an example of inventory protection.